Environmental Science: Nano最新文献

Chili peppers (Capsicum annuum L.) have a high postharvest metabolism, causing moisture loss and microbial spoilage, which shortens their shelf life, thereby imposing environmental burdens through resource waste, greenhouse gas emissions, and secondary pollution. Carbon dots (CDs), zero-dimensional carbon-based nanomaterials with particle sizes below 10 nm, show promise in food packaging and postharvest preservation. In this study, a chitosan/N-CD (CS/N-CD) composite material was developed with superior barrier, antioxidant activity, and antibacterial properties. CS/N-CD films with different N-CD ratios showed good compatibility, enhanced UV absorption, improved barrier properties (0.5% film with 11.4% lower WVP), and higher antioxidant activity (2.5% film with 66.8% DPPH scavenging). The 0.5% films showed high antibacterial rates against Escherichia coli and Staphylococcus aureus (89.2–99.6% vs. 14.9–62.5% for pure CS). After being applied to chili pepper fruits via spraying, dipping, and film-coating, the material reduced weight loss and preserved fruit firmness (2.5-fold reduction by day 21 vs. 4.8-fold for the control). High-throughput 16S rRNA gene sequencing showed that CS/N-CDs altered the microbial structure; dipping increased Actinobacteria by 355.4% and suppressed Enterobacter by 98.2%, while spraying reduced Enterobacter by 82.9% and enriched Pseudomonas by 87.1%, thereby improving the microbial microenvironment during storage of the chili pepper fruit. These results show that the CS/N-CD composite exerts a synergistic preservation through a physical barrier and microbial modulation. Given the eco-friendly properties of CS/N-CDs, these findings offer insights into advancing sustainable nanocomposite-enabled postharvest preservation.

Wide application and release of engineered nanomaterials (ENMs) into the environment require an understanding of their potential ecological impacts, particularly under real environmental conditions. Previously we reported that low doses of photoexcited ENMs exert significant sublethal stress on bacterial outer membranes in a freshwater medium, potentially increasing bacterial susceptibility to viral infection and promoting microbial evolution and diversity. However, little is known about how ENMs may affect bacteriophage infection under environmental conditions. Therefore, this study investigates the effects of commonly used photoactive ENMs – n-TiO₂, n-Ag, and their mixtures – on the infection of a filamentous coliphage, bacteriophage f1, at environmentally relevant concentrations under freshwater conditions. We also interrogate cellular surface properties and the expression of key genes associated with phage–cell interactions in response to ENM exposure. Under light, n-TiO₂ or n-Ag increases bacteriophage infection, consistent with trends showing increased outer membrane permeability (OMP), F-pili-related gene expression, and pili density. Exposure to n-TiO₂ + n-Ag mixtures under light, however, suppresses the effects of the individual ENMs on bacteriophage infection, despite high OMP, amplified up-regulation in F-pili and membrane protein expression, and augmented pili density. We propose that greater oxidative stress on the cell membrane induced by the photoexcited ENM mixtures in comparison to individual ENM exposure, as previously detailed, damages membrane proteins (e.g., TolA) vital to bacteriophage entry and dominates other mechanisms. Overall, our results provide mechanistic insight into the complex interactions among bacteria, bacteriophage, and ENMs, under environmentally relevant conditions, and further detail their potential ecological risks.

Nanoplastics (NPs) are emerging environmental contaminants with the potential to induce cellular stress and immune dysregulation in aquatic organisms. In this study, the freshwater leech Hirudo verbana was used as a non-conventional invertebrate model to investigate the effects of acute (24–72 hours) and chronic (1 week–1 month) exposure to polyethylene terephthalate nanoplastics (PET NPs). A multidisciplinary approach combining microscopy, histology, immunocytochemistry, and qPCR was employed to evaluate PET NP uptake and biological responses. PET NPs were internalised in leech tissues and detected in macrophage-like cells. Both exposure regimes triggered a time- and dose-dependent inflammatory response, characterised by macrophage-like cell recruitment, angiogenic remodelling, and upregulation of the pro-inflammatory marker HmAIF-1. Endothelial activation was confirmed by increased CD31 expression and neovascularisation. Furthermore, oxidative stress was evidenced by altered expression of glutathione S-transferase (GST) and superoxide dismutase (SOD) genes. Overall, PET NPs induced conserved immune and stress responses in H. verbana, supporting its relevance as an alternative model for nanoplastic ecotoxicology. These findings contribute to our understanding of NP-induced pathophysiology and reinforce the need for further investigation into the ecological impact of plastic pollution on freshwater invertebrates.

The present study investigates the potential of seed priming with calcium oxide nanoparticles (CaO NPs) to enhance arbuscular mycorrhizal fungal (AMF) colonization, helpful to mitigate NaCl stress in rice (Oryza sativa L.) under controlled pot culture conditions. Rice seeds were initially surface sterilized and primed with CaO NPs (80 ppm). The primed seeds were grown with or without AMF inoculation in soil pre-treated with 175 mM NaCl to impose NaCl stress. Non-stressed and untreated plants served as controls. The combined AMF and CaO NP treatment increased root mycorrhizal colonization by 32% and soil flavonoid exudation by 33% (P < 0.05). Under NaCl stress, reducing sugars increased by 149% and non-reducing sugars decreased by 66%; however, these changes were moderate in plants subjected to AMF and CaO NP co-application treatment, where reducing sugars increased only 110% and non-reducing sugars decreased by 38%. Antioxidant regulation also improved, with reduced glutathione and total glutathione increasing by 139% and 168%, respectively, along with a higher net photosynthetic rate compared with the control. Furthermore, co-application improved ionic homeostasis, with a 35% increase in Ca²⁺ uptake and 58% reduction in Na⁺ accumulation compared to NaCl-stressed plants. Collectively, these results demonstrate that CaO NP seed priming amplifies AMF symbiosis both structurally and functionally, safeguarding photosynthetic efficiency and enhancing rice tolerance to salinity. This synergistic bio–nanotechnological approach offers a sustainable strategy for improving crop resilience in saline environments.

Nano-enabled agriculture has greatly improved the yield and quality of agricultural products, and reduced pesticide usage and environmental pollution. However, the building of intelligent nano-pesticides and devices for sustainable disease management still poses severe challenges in modern agriculture. Herein, a smart pH and pectinase dual-responsive pesticide microcapsule was constructed and used to create an adhesive gel patch for disease management. Employing prochloraz (PRO) ionic liquid as a soft template, a metal–phenolic network and pectin were coated to respond to oxalic acid and pectinase secreted by Sclerotinia sclerotiorum during its infection of plants. The preparation of microcapsules was accomplished rapidly, economically, and in an eco-friendly manner in an aqueous environment. The microcapsules exhibited pH and pectinase-dual-responsive traits. The photostability of the microcapsules is 1.33 times that of PRO EW. Fungicidal testing indicated that the control effect of the microcapsules is 1.47 times that of PRO EW. Pot experiments revealed that the control effect of the microcapsules is 2.98 times that of PRO EW. To further enhance the long-term autonomous management and minimize the drug leakage of traditional spraying methods, an adhesive gel patch containing the microcapsules was developed. Using agar hydrogel to stabilize the microcapsules and silicone rubber as a protective layer, the patch can adhere to the leaves under the action of a magnet. With the same dosage of PRO, the management period of the adhesive gel patch was twice as long as that of the spraying method. This study offers a novel strategy for achieving the sustainable management of plant diseases and precision agriculture.

Iron (Fe) is an essential nutrient for plant growth, yet its bio-availability in soil is often restricted, limiting crop productivity. Conventional iron fertilizers, such as iron salts and chelates, suffer from inefficiencies and contribute to environmental concerns, including leaching and soil acidification. This study explores the use of jellyfish-based hydrogels as a slow-release carrier for iron-oxide nanoparticles (Fe-NPs) to enhance iron bio-availability in agricultural soils. Jellyfish-derived biomaterials offer a sustainable and biodegradable matrix with high water retention and tunable gel properties, making them an effective medium for controlled nutrient release. In this study, iron release was examined across various hydrogel formulations and environmental conditions to assess factors influencing nutrient bio-availability. The results demonstrate that iron release is highly dependent on hydrogel formulation, with key factors including hydrogel strength and the method of iron loading, such as nanoparticle selection and cross-linking with iron ions. Hydrogels cross-linked with iron ions released iron more rapidly than those cross-linked with calcium, while Fe₃O₄-containing hydrogels exhibited faster release than those incorporating Fe(OH)₃ nanoparticles. Additionally, monovalent ions accelerated hydrogel degradation through ion exchange, leading to increased iron release. Soil suspension experiments further confirmed that monovalent ions are a primary driver of hydrogel breakdown and iron release, whereas microbial activity has minimal impact on iron release. These findings highlight jellyfish-based hydrogels as an effective and biodegradable slow-release system, capable of modulating iron bio-availability based on environmental and soil conditions. This approach offers a promising, sustainable alternative to conventional iron fertilizers.

Copper is widely used to control various plant diseases and recent trends highlight the prominence of copper-based nanomaterials in developing new nanoagrochemicals. As these nanomaterials eventually end up in the aquatic environment, they necessitate increased attention regarding their environmental and human health risks. Herein, we demonstrate the use of metal–phenolic network (MPN) nanocomposites as novel agents for mitigating the toxicity of copper oxide (CuO) nanoparticles (NPs), which exert toxicity mainly through released Cu ions. Iron–tannic acid-based porous 3D networks on gold NP cores (Fe–TA@Au NPs) exhibited the capacity to reduce CuO NP toxicity in freshwater protozoa Tetrahymena thermophila – a model for environmental toxicity, and in human macrophages – an in vitro model for human safety. In the macrophage assays, Fe–TA@Au NPs increased the half-effective concentration (EC₅₀) of CuO NPs by approximately three-fold, from 4.7 mg L⁻¹ to 15.4 mg L⁻¹. This mitigation occurred through two main mechanisms: adsorption of Cu ions, released from CuO NPs, and reduction of intracellular reactive oxygen species, both of which contributed to the toxicity of CuO NPs. The maximum adsorption capacity for Cu²⁺ was 172 mg g⁻¹ of Fe–TA MPN, comparable to other copper adsorbents, including MPNs and metal–organic frameworks (MOFs). Additionally, Fe–TA@Au NPs demonstrated excellent biocompatibility and ecosafety in a highly sensitive microalgal growth inhibition assay and exhibited long-term efficacy, indicating the strong potential of these porous materials in mitigating copper toxicity. Furthermore, the gold NP cores in the MPN model used in this study can easily be replaced with other core NP materials, making them suitable for large-scale environmental and human health applications.

In this study, we present an eco-friendly approach for the synthesis of fluorescent carbon dots (CDs) using the extracellular supernatant of Bacillus sp. NBSG24, a soil-derived bacterium. The supernatant contains a diverse mixture of biomolecules, including proteins, enzymes, lipids, polysaccharides, and other soluble components of the bacterial secretome, which serve as natural precursors for carbon dot formation. The resulting NB24@CDs exhibit bright blue fluorescence, excellent water solubility, and high stability under rigorous conditions, including changes in pH, ionic strength, UV exposure, and prolonged storage. Notably, these CDs are intrinsically doped with nitrogen and sulfur atoms, originating from the bacterial extracellular metabolites, leading to enhanced optical properties and sensing capabilities. A key feature of NB24@CDs is their ability to rapidly and selectively detect hexavalent chromium (Cr⁶⁺), a highly toxic and environmentally persistent contaminant. Upon exposure to Cr⁶⁺, the fluorescence of NB24@CDs is quenched rapidly within 10 seconds, indicating a fluorescence “turn-off” response. The system exhibits a low detection limit of 30 nM (1.56 μg L⁻¹), substantially lower than the World Health Organization (WHO) permissible limit of 962 nM (50 μg L⁻¹) for Cr⁶⁺ in drinking water. Additionally, the sensing platform performs reliably in real water samples such as tap, river, and lake water, without interference from common coexisting ions. Spectroscopic analysis, including fluorescence lifetime, UV-vis, FTIR, and XPS, suggest that the detection mechanism involves static quenching due to complex formation with Cr⁶⁺, along with partial reduction of the metal ion. Overall, this work highlights the potential of microbial-derived, heteroatom-doped CDs as a sustainable, cost-effective, and scalable solution for environmental monitoring of toxic heavy metals.

Peanut smut, caused by Thecaphora frezii, leads to severe annual yield losses worldwide, particularly in Córdoba, Argentina. The fungicide Thiram (tetramethylthiuram disulfide) is widely used to control this disease, but its low aqueous solubility (∼30 mg L⁻¹) is a major limitation to its application. Nanocarriers could enhance Thiram's solubility and stability, possibly increasing its efficiency in agricultural applications. To test this in our laboratory, Thiram was encapsulated in two different delivery systems: a) zirconium-based MOF-808 nanocrystals (nMOF-808) and b) Tween 80/Span 80 (1 : 1) niosomes. nMOF-808 was able to incorporate up to 2 g of the fungicide per gram of absorbent and keep it colloidally stable in aqueous suspension for one day. On the other hand, in the presence of niosomes, it was possible to dissolve up to 0.1 mM Thiram in a colloidally stable form for approximately one month under appropriate conditions. Both systems proved to be photoprotective for the fungicide and were capable of controlled release of the encapsulated Thiram. The incorporation of Thiram into nMOF-808 could be interpreted according to the Langmuir model and kinetically by the intraparticle diffusion model, which is uncommon in the literature for the adsorption of neutral molecules in MOFs. These laboratory results indicate that the studied nanoplatforms are promising for future field studies aimed at optimizing efficiency and sustainability in the control of peanut smut and other fungal diseases.

Environmental stress conditions such as drought, salinity, and heavy metal toxicity can considerably reduce growth and productivity of plants. Nanotechnology offers efficient solutions to enhance plant growth under stressful environments. Nanoparticles (NPs; 1–100 nm) in the form of plant growth promoters, nanopesticides, and nanofertilizers improve the nutrient use efficiency, stress resistance, and soil cleaning and minimize environmental pollution. Nanoparticles also transform plant–microbe associations through the modulation of rhizosphere microbial populations as well as root exudation, influencing the health of the plant as well as ecosystem services. Their nanoscale size and huge surface area facilitate enhanced physiological action and mobility as well as uptake within plant systems, frequently leading to enhanced growth and yield. However, these same traits can also cause toxicity. Therefore, it is important to carefully consider the NPs' size-dependent effects. This review highlights the significance of particle size in plant–NP interactions, with a particular emphasis on their dual potential to cause toxicity and mitigate environmental stress. This is, to the best of our knowledge, the first thorough evaluation of size-dependent NP effects on plants and related microbes. The significance of creating safe, optimized nanomaterials that provide agronomic advantages with little ecological risk is also highlighted.